In current times where computers and tablet computers are increasingly important for writing, handwriting too is becoming a more niche market with increasing demands, especially regarding fountain pens. One of the most important advantages of handwriting versus computers or such is the high autonomy and independence of electricity.
Fountain pens have an internal ink reservoir that can be filled in various manners. Early fountain pens for example used an eyedropper system wherein the nib unit had to be removed from the reservoir for refill. Such filling systems however are conceived as messy, time consuming and hence impractical.
Other fountain pens are provided with a piston movable to-and-fro the cylinder reservoir for refilling the pen through the pen nib. The piston can be actuated by a piston rod fixedly attached to the piston body and protruding through the distal end of the cylinder. This construction has the disadvantage that when the reservoir is filled the piston rod projects a substantial axial distance beyond the distal end of the cylinder. As a consequence the piston mechanism takes up a relatively large portion of the space available in the pen barrel and therefore restricts the maximum length of the cylinder and hence the volume of the Ink chamber within it and the autonomy of the pen.
U.S. Pat. No. 6,270,276 addresses the above problem and as a solution provides a fountain pen with a refillable cylinder reservoir wherein a piston body is slideably accommodated and is actuated by a rod that is releasably fixed to the piston body and extends through a channel in said piston body. In order to actuate the piston body, the piston rod is retreated from the cylinder until the frontal end of the piston rod contacts the piston body and is fixed thereto by means of a screw thread connection. Once fixed the piston body can be pushed to-and-fro in the cylinder to fill or refill the cylinder. After refill, the piston rod is unscrewed from the piston body and pushed into the cylinder. As such nearly the entire shaft of the pen can be used as ink reservoir, thereby considerably increasing the pen's autonomy.
An inconvenience of a fountain pen as disclosed in U.S. Pat. No. 6,270,276 is that when the piston body is not actuated for a while, slip-stick phenomena occur inhibiting gently pushing the piston body to the frontal end of the reservoir. As a relatively large force is needed to overcome the slip-stick phenomena, the piston body will be pushed forward with high speed and air and ink present in the reservoir will be pushed out suddenly and in an uncontrolled manner leading to spilling.
Furthermore, when after filling, the piston rod is to be unscrewed from the piston body, rotation of the piston body in the cylinder will prevent such unscrewing and urge the user to exert a radial force on the piston rod to block the piston body in the cylinder to allow unscrewing, however at the cost of potentially damaging the fountain pen.
From the above it is clear that there remains a need for providing n easy to use fountain pen with a large autonomy.